Airworthiness Directive · Amendment 39-17336 · Tail rotor head
Eurocopter France Helicopters
This AD applies to Eurocopter Model EC 155B, EC155B1, SA-365N1, AS-365N2 and AS 365 N3 helicopters with a 10-bladed tail rotor hub (TRH), part number (P/N) 365A33351100, 365A33351101, or 365A33351102 installed; and Model AS 365 N3 helicopters with an 11-bladed TRH, P/N 365A33216001or 365A33216003, installed, certificated in any category.
We are superseding an existing airworthiness directive (AD) for Eurocopter France (Eurocopter) Model EC 155B, EC155B1, SA-365N1, AS-365N2 and AS 365 N3 helicopters. That AD currently requires inspecting certain tail rotor hubs (TRH) for a crack and removing any cracked TRH. This AD requires the same actions but adds more part numbers to the list of affected TRHs. This AD is prompted by further analysis that indicates that additional part-numbered TRHs must be inspected for cracks. The actions specified by this AD are intended to detect a crack in the TRH and prevent the tail rotor from jamming, which could lead to reduced or loss of control of the helicopter.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) Within 55 hours time-in-service (TIS), and thereafter at intervals not to exceed 55 hours TIS, using a light, visually inspect the TRH for a crack in the entire area shown as Area C of the TRH in Figure 1 of Eurocopter Alert Service Bulletin (ASB) No. EC155-05A021, Revision 1, dated July 20, 2011, or ASB No. AS365-05.00.60, Revision 2, dated October 9, 2012, as applicable to your helicopter model. The inspection area is on the tail gearbox (TGB) side of the TRH. The TGB is shown as (c) in figures 2 and 3 of the ASBs. You must pay particular attention to the area around the screws, shown as (e) in Figure 3 of the ASBs, and the TRH between the lower part of the TGB and its fairing, shown as (d) in figures 2 and 3 of the ASBs, using details D and E of Figure 3 in the ASBs. You must turn the tail rotor by hand to inspect the entire Area C.
(2) If there is a crack on the TRH, remove the TRH from service.
